1. Field of the Invention
Embodiments of the present invention generally relate to plasma-assisted processing of substrates, and more particularly, to magnetic confinement of a plasma in plasma-assisted substrate processing chamber.
2. Description of the Related Art
Plasma-assisted processing is a technique commonly used, for example, in the manufacture of semiconductor devices and integrated circuits. Such processing generally includes introducing a process gas into a chamber having a substrate, such as a semiconductor wafer, disposed therein and applying sufficient energy to the process gas to form a plasma over the substrate. The plasma contains dissociated and ionized components as well as neutral components that operate to assist the process being performed on the substrate (such as deposition, etching, and the like). Although the constituents of the plasma are beneficial for assisting or carrying out the process on the substrate, it is often undesirable for the plasma constituents to come into contact with other components within the process chamber, such as the substrate support, sidewalls, or lid of the chamber. As such, it is often desirable to try to contain or limit the plasma to a region directly over the substrate being processed.
This problem has been conventionally addressed by the use of mechanisms for physically confining the plasma in the desired area. For example, certain process chambers may contain baffles that physically constrain the plasma within a desired area. However, these baffles transfer the problem from one of the plasma contamination or attack of the process chamber to plasma attack or contamination of the baffles themselves. As such, the baffles become a consumable material that may contribute to particulate defects on the substrate and further require periodic maintenance or replacement. In addition, physical confinement of the plasma using baffles restricts the ability to pump out plasma effluent from the chamber, thereby further degrading process performance and potentially leading to substandard process throughput and increased substrate defects.
Therefore, a need exists for an improved method and apparatus for confining a plasma in a process chamber.